crossbow

n. bow shaped weapon from which arrows are fired

A crossbow is a weapon consisting of a bow mounted on a stock that shoots projectiles. A mechanism in the stock holds the bow in its fully-drawn position until it is shot by releasing a trigger. Crossbows played a significant role in the warfare of North Africa, Europe and Asia. Crossbows are used today primarily for target shooting and hunting.
See more at Wikipedia.org...

Noun
1. a bow fixed transversely on a wooden stock grooved to direct the arrow (quarrel)
(hypernym) bow

(n.)
A weapon, used in discharging arrows, formed by placing a bow crosswise on a stock.
  

(see Arbalest )